Theirs is not a traditional teacher-student relationship: Mr. Miller is not a Yalie. He’s never even been to the U.S. He’s an aircraft mechanic in Kilmarnock, Scotland, who downloaded the professor’s Greek history lectures from the Internet and listened to them as he worked on airplane engines. “I was just telling someone last week about the city of Troy,” says Mr. Miller, 32.

MIT professor Michael J. Cima says he was skeptical of the educational benefits of online courses. Now, he embraces the Web as a teaching tool. His chemistry class is featured on the non-profit site edX.

The Web’s most popular instructors and professors say they are getting recognized at restaurants and on city buses and are gaining new entry to potentially lucrative speakers’ circuits. Non-university instructors who create skill-based classes draw direct revenue from the popularity of their classes—plus the perks of personal branding and promotion.

Universities are signing up in droves with websites that stream lectures. One of the fastest-growing categories of videos on YouTube, according to the site, are “tuts”—pronounced “toots” and short for “tutorials.”

Victor Bastos, a 32-year-old Internet developer from Lisbon, Portugal, got discovered by talent scouts from Udemy Inc., a website where instructors offer classes. Mr. Bastos had been posting homemade instructional videos to YouTube. Employees at Udemy happened upon them and contacted him. They helped him create an entire curriculum, spruce up his production and increase his social-media outreach. Since the fall of 2011, more than 6,000 students have paid for his “Become a Web Developer From Scratch” class, which retails for $199. Mr. Bastos has netted more than $250,000 in revenue. “I never expected it to get so big,” says Mr. Bastos, who has quit his day job to focus full-time on teaching. Carol Ann Waugh, 64, retired from a career in educational publishing and began to teach a quilting class called Stupendous Stitching in November 2011 for Craftsy, a Denver-based education website for craft aficionados that charges between $20 and $50 for many of its classes and shares revenue with its teachers. About 12,000 paying students have since enrolled. Ms. Waugh self-published a book, also called “Stupendous Stitching,” which she says has sold briskly among her students and local quilting-shop customers. Ms. Waugh had never taught before. At the QuiltCon convention in Austin, Texas, in February, she was stopped by 20 students who recognized her. “It’s embarrassing, actually,” she says.

While early-adopting instructors began posting their lectures online nearly two decades ago, today’s platforms provide a sleek experience for students looking for well-produced content instead of video coming from one camera in the back of a dark lecture hall.

University of Pennsylvania professor Al Filreis had 36,000 poetry students thanks to Coursera.

The viral success of instructional videos made by former hedge-fund analyst Salman Khan initially demonstrated the broad appeal of tuts. Today, his Khan Academy offers 4,000 free math and science videos for grade- and high-school students. The site became a blueprint for how interactive technology could improve the e-school experience. EdX, which features classes from Harvard University and Massachusetts Institute of Technology, among others, launched in May 2012 and now has more than 700,000 users. Udemy launched in 2010 as an online education marketplace that helps people create and sell online classes. The site counted 500,000 enrolled students in December 2012, the same month it received $12 million from venture investors, after starting with 100,000 enrollees that January. Coursera last month announced that 29 schools, including Northwestern University, have joined those like Duke University and Hong KongUniversity of Science and Technology in offering some of its classes online through Coursera’s platform. Sixty-two schools around the world now feed the site.

Professors invest time and attention in creating lecture segments of between 10 and 20 Web-friendly minutes. In cases when it benefits the production value, they deliver these lectures without students present, even though they likely are teaching similar material to real-life students.

To compete with Coursera, edX and others, Udemy has started to recruit university professors to offer classes on its site. Since Udemy began hosting “Math is Everywhere: Applications of Finite Math,” taught by Tim Chartier, a math professor at Davidson College in Davidson, N.C., Prof. Chartier has been asked to present research at a seminar and contacted for an interview by a professional journal, both thanks in part to his newfound exposure. Nearly 5,500 students have taken Prof. Chartier’s class on Udemy. (He teaches 30 students at a time in person for that course.) The site just launched his March MATHness course meant to help NCAA basketball fans use math to pick their tournament brackets.

Prof. Chartier says the greatest perk to his Udemy experience is that it has helped him rethink how best to teach students in his actual classroom. In shaping classes for Web platforms, Prof. Chartier has learned to create mini-lectures that explain a single idea in about 10 minutes. This semester he has tested this approach on his Davidson students, asking them to watch a mini-lecture before class. “This has stimulated class discussion so much,” he says.

Seth Kindig, a 21-year-old math major at Davidson College, takes Prof. Chartier’s Math Modeling class. Mr. Kindig received a text last month from a friend in Georgia asking if he knew Prof. Chartier. The friend was studying math under the professor via Udemy. “I didn’t realize he was that big of a deal,” Mr. Kindig says.

Young adults aren’t the only members of these expanded academic audiences, either. “I had a student introduce himself and say, ‘You know, my father is taking this class, too,'” says Michael J. Cima, an MIT professor whose Introduction to Solid State Chemistry class is available on edX.

University professors—stereotyped to consider research more relevant to career advancement than teaching—are now getting in line to get online, says Robert Lue, a professor of molecular and cellular biology at Harvard University who oversees Harvard’s contribution to edX. Prof. Lue recalls little interest among his peers in distance learning five years ago. Now he has a queue of 80 professors who want to teach through edX. “We are drowning in goodness,” he says.

Carol Ann Waugh teaches a quilting class for Craftsy.

Al Filreis, a professor of English at the University of Pennsylvania, has been posting his lectures online for about 17 years. This past fall, Coursera made his Modern Poetry class available on its site. Thirty-six thousand students enrolled from 126 countries. “This is like joining the club of people who have giant megaphones,” he says.

Yale’s Prof. Kagan, a star on his New Haven, Conn., campus long before the Internet came along, says he sees plenty of benefits to exposing people all over the world to information that for so long was available to very few.

Still, he believes that the availability of his lectures, posted online by the site Yale Open Courses, results in some Yale students’ choosing not to enroll in his classes because they can “watch the lectures on television,” he says, adding, “I’m not sure anything can replicate the kind of learning that can happen in person.”

One Response to Online Teaching, by Katherine Rosman

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